This Demonstration calculates and plots the steady state heat flow per unit area,

(in watts/

), through an insulated or uninsulated wall. You can choose the wall's thickness,

(in cm), and its thermal conductivity,

(in watts/m °C); the insulation's thickness,

(in cm), and its thermal conductivity,

(in watts/m °C); the surface heat transfer coefficients at either side of the wall,

and

(in

°C); and the temperature difference,

(in °C), between the inside and outside. The calculations are done using the equation

, whose parameters can be modified by moving the sliders. The red dot on the plot marks the flow rate per unit area for a

chosen by moving the top slider. The top graphic depicts the heat resistances as a schematic diagram (not to scale).